This invention relates to machines and methods for manufacturing articles made up of multiple layers of materials and/or strips.
Numerous machines are known in the prior art for separately moving lines of sheets and/or strips to an assembly location and attaching the sheets and/or strips to produce an assembled article. For example, the S. R. Schleven U.S. Pat. No. 3,618,838 describes a conveyor mechanism for carrying separate layers of webs to an assembly area and forming a multilayered structure. The conveyor is formed by a series of trucks which form a rigid support surface, and the layers are held by vacuum on the trucks.
In some instances the webs or strips initially extend in the direction of the line of movement of the conveyor, and it is desirable to rotate segments of a selected web or strip so that the segments extend at an angle to the initial line of movement. For example, the M. B. Lucas U.S. Pat. No. 3,269,516 (assigned to The Procter & Gamble Company), and the prior art discussed in this patent, disclose machines for manufacturing disposable diaper pads formed from flexible sheet material. During the manufacture, each diaper pad is rotated through an angle by a turning mechanism. The M. B. Lucas patent discloses a machine including a series of turning heads that are moved by a chain conveyor, each turning head carrying a pad, and a turning mechanism rotates the turning head. Since, as shown by the drawings of the Lucas patent, adjacent turning heads are spaced a substantial distance apart, the heads may be rotated by the turning mechanism without interference between adjacent heads.
In some instances, however, an essentially continuous rigid support surface formed by a series of closely adjacent plates or heads is desired. In this situation, turning of a head would be obstructed by a closely adjacent head. To overcome this problem, some machines of this character have been provided with mechanisms for shifting a head out of the plane of the adjacent heads, turning the head while so shifted and then returning the head to the plane of the adjacent heads. Such an arrangement, however, requires rather complex mechanisms for both shifting and turning a head, and this is particularly true in a machine that also has a vacuum arrangement for holding a strip or sheet on the head.
It is therefore a general object of the present invention to provide an improved machine and method for assembling sheets and/or strips, including improved means for turning tables that carry sheets or strips.